public class BinarySearchTree {

    //时间复杂度 最好情况 O(logN) 完全二叉树
    //         最差情况 O(N)   完全为左,完全为右
    static class TreeNode{
        public int val;
        public TreeNode left;
        public TreeNode right;


        public TreeNode(int val){
            this.val=val;
        }
    }

    public TreeNode root;


    //插入数据
    public void insert(int key){
        if(root==null){
            root=new TreeNode(key);
            return ;
        }
        TreeNode cur=root;
        TreeNode parent=null;
        TreeNode node=new TreeNode(key);
        while(cur!=null){
            if(cur.val<key){
                parent=cur;
                cur=cur.right;
            }else if(cur.val>key){
                parent=cur;
                cur=cur.left;
            }else {
                return;
            }
        }
        if(parent.val>key){
            parent.left=node;
        }else {
            parent.right=node;
        }
    }

    //查找数据
    public TreeNode search(int val){
        TreeNode cur=root;
        while (cur!=null){
           if(cur.val>val){
               cur=cur.left;
           }else if(cur.val<val){
               cur=cur.right;
           }else{
               return cur;
           }
        }
        return null;
    }

    //删除数据
    public void remove(int key){
        TreeNode cur=root;
        TreeNode parent=null;
        while(cur!=null){
            if(cur.val<key){
                parent=cur;
                cur=cur.right;
            }else if(cur.val>key){
                parent=cur;
                cur=cur.left;
            }else {
                removeNode(parent,cur);
                return;
            }
    }
}

    private void removeNode(TreeNode parent, TreeNode cur) {
        if(cur.left==null){
            if(cur==root){
                root=cur.right;
            }else if(parent.left==cur){
                parent.left=cur.right;
            }else{
                parent.right=cur.right;
            }
        }else if(cur.right==null){
            if(cur==root){
                root=cur.left;
            }else if(parent.left==cur){
                parent.left=cur.left;
            }else{
                parent.right=cur.left;
            }
        }else{
            TreeNode targetParent=cur;
            TreeNode target=cur.right;
            while(target.left!=null){
                targetParent=target;
                target=target.left;
            }
            cur.val=target.val;
            if(targetParent.left==target){
                targetParent.left=target.right;
            }else {
                targetParent.right=target.right;
            }
        }
    }
}
